Piggyback dual lock bar

ABSTRACT

An emergency locking safety belt retractor mechanism includes a belt winding reel, at least one reel associated ratchet member having a plurality of ratchet teeth, dual locking pawl means mounted for engaging the ratchet teeth of the ratchet member and inertia responsive means for actuating one of the locking pawl means into locking engagement with the associated ratchet member. The dual locking pawl means include a pair of locking pawls mounted to the retractor in piggyback or overlying relation such that in the event the first locking pawl fails to lock with the ratchet member because of a pawl bounce condition, its deflective motion away from the ratchet member causes it to engage and move the second locking pawl into a locking condition with ratchet member, locking the reel against further protraction of the webbing.

United States Patent 1 Ziv PIGGYBACK DUAL LOCK BAR Avraham Ziv,Sepulveda, Calif.

American Safety Equipment Corporation, Encino, Calif.

Filed: Apr. 10, 1974 Appl. No.: 459,539

Inventor:

Assignee:

References Cited UNITED STATES PATENTS 2/1964 Whittingham 242/107.48/1968 Hansen 242/1074 5/1971 Kell 242/1074 1 June 17, 1975 PrimaryExaminer-George F. Mautz [57] ABSTRACT An emergency locking safety beltretractor mechanism includes a belt winding reel. at least one reelassociated ratchet member having a plurality of ratchet teeth, duallocking pawl means mounted for engaging the ratchet teeth of the ratchetmember and inertia responsive means for actuating one of the lockingpawl means into locking engagement with the associated ratchet member.The dual locking pawl means include a pair of locking pawls mounted tothe retractor in piggyback or overlying relation such that in the eventthe first locking pawl fails to lock with the ratchet member because ofa pawl bounce condition, its deflective motion away from the ratchetmember causes it to engage and move the second locking pawl into alocking condition with ratchet member, locking the reel against furtherprotraction of the webbing.

7 Claims, 6 Drawing Figures PATENTEIJJUN l 7 I975 E H- 8 89 L 8 98PIGGYBACK DUAL LOCK BAR BACKGROUND OF THE INVENTION This inventionrelates in general to emergency locking safety belt retractor mechanismsfor use in adjustably anchoring safety belts of seat belt and/or harnessassemblies employed for restraining passengers in vehicle seats duringemergency conditions. More particularly, the present invention relatesto a fail safe locking mechanism for inertia locking safety beltretractors as aforedescribed wherein a dual locking pawl means isprovided such that one or the other thereof will assuredly lock theretractor upon an emergency condition experienced by the vehicle.

Emergency locking retractor mechanisms of various types have beendeveloped and placed into commercial use heretofore wherein the lockingpawl means have been actuated manually, automatically on a protractionmovement of the webbing or an acceleration thereof above a predeterminedrate, and in response to changes in inertia of the vehicle in which themechanism is mounted. In all of these types of retractors, particularlywherein a ratchet wheel associated with the webbing storage reel isprovided for engagement by a locking pawl, a pawl bounce condition canoccur. It has been found, particularly in the dynamic conditionsexperienced during emergency conditions encountered by a moving vehicle,that it is possible for the tip ofa locking pawl to come into engagementwith the tip of a tooth of the ratchet wheel member in such manner thatthe pawl is rebounded or deflected away from the ratchet wheel ratherthan moving into a locking engagement with the ratchet wheel and thuspreventing further pro traction of the webbing. The failure of thelocking pawl to lock up in the so called pawl bounce condition allowsundesired protraction of the webbing which may cause a reduction in theefficiency of operation of the retractor mechanism.

It has therefore been recognized that a locking pawl means for emergencylocking retractors is needed which will lock up assuredly underemergency conditions even though a pawl bounce" condition may occurwherein the leading edge or tip of the pawl fails to clear the leadingedge of the oncoming tooth of the ratchet wheel revolving in response toprotraction of the webbing in an emergency situation. There have beenprior attempts to solve this problem through the provision of duallocking pawl mechanisms of various types. However, it is believed thatnone of these prior attempts have included mechanisms having aconstruction or mode of operation, as contemplated for the withininvention wherein a second pawl of the locking pawl means is actuated inresponse to the movement of the first pawl means imparted by theoccurrence of a pawl bounce condition.

SUMMARY OF THE INVENTION Therefore it is the primary object of thepresent invention to disclose and provide an improvement in locking pawlmeans for emergency locking safety belt retractor mechanisms which willprovide for a positive and assured lock up of the retractor upon anemergency condition even though the primary locking pawl may encounter afalse locking or pawl bounce condition.

It is the further object of the present invention to disclose andprovide an improvement in locking pawl means as in the foregoing objectwherein the actuation or movement of a secondary or fail safe lockingpawl is provided by the deflective or bounce movement of the primarylocking pawl away from the associated ratchet member provided inassociation with the belt storage reel.

It is a still further object of the present invention to disclose andprovide an improvement in locking paw] means as in the foregoing objectswherein a novel construction and mode of operation is provided by a pairof locking pawls co-operating together to provide for a positive andassured lock up of the retractor ratchet wheel associated with thewebbing or safety belt wherein the energy or momentum imparted in alocking failure or paw] bounce condition to the primary locking pawl isimparted directly and positively to the secondary locking pawl to causeit to promptly and positively lock the retractor reel against furtherundesired protraction of the webbing or safety belt.

Generally, the apparatus according to the present invention, is suitablefor use in various types of emergency locking safety belt retractorshaving a locking pawl for preventing belt protraction from the retractorby engagement with a tooth ofa ratchet wheel member. having a pluralityof ratchet teeth, associated with the belt re-wind reel. In addition tothe primary locking pawl noted, a fail safe locking pawl is providedtogether with means for mounting it to the retractor in position to bemoved into engagement with the teeth of the ratchet wheel member. Asparticularly contemplated within the present invention, means areprovided for movably mounting the primary locking pawl to provide forits movement against the fail safe pawl to move the latter into lockingengagement with a ratchet tooth upon a deflective movement of theprimary locking pawl relative to the ratchet member, as when the primarylocking pawl engages a tip of a ratchet tooth in a so called pawl bouncecondition and is deflected away from such member.

More particularly, the means for mounting the fail safe locking pawlmounted with its forward ratchet engaging portions in generally adjacentand overlying relation to rearward portions of the primary locking pawl,which is pivotally mounted to the retractor mechanism. Upon actuation ofthe primary pawl, due to an emergency condition sensed by the retractormechanism, the primary pawl will normally engage the ratchet reel andlock up the mechanism. However, ifa leading edge of the primary lockingpawl engages the leading tip of the on-coming ratchet wheel tooth and isdeflected thereby, means are provided for mounting the primary lockingpawl so that it will pivot about an approximate mid portion, midwaybetween the leading and trailing edges thereof, and bring a rearwardportion thereof up under the leading edge of the fail safe pawl, movingthe latter into locking engagement with the tooth of the ratchet wheelin a positive, fail safe manner. Undue protraction of the webbing orsafety belt associated with the mechanism is thereby avoided.

The various advantages and improvements of the present invention inlocking pawl means for emergency locking safety belt retractors, as wellas a better understanding thereof, will be obtained by those skilled inthe art from a consideration of the following detailed description of apreferred exemplary embodiment of the present invention. Reference willbe made to the appended sheets of drawings which will be describedbriefly before the detailed description of the preferred exemplaryembodiment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an elevational view of anexemplary emergency locking safety belt retractor mechanism of thevehicle inertia responsive type employing the improvement in lockingpawl means in accordance with the present invention;

FIG. 2 is a side elevation of the retractor mechanism of FIG. 1 takentherein along the plane IIII;

FIG. 3 is a detail section view of the improvement in locking pawl meansof the retractor mechanism of FIG 1 taken therein along the planeIII-Ill showing the locking pawl means and associated vehicle inertiaresponsive means in a rest position;

FIG. 4 is a view of the mechanism of FIG. 3 showing the normal lockingmode thereof;

FIG. 5 is a view of the mechanism of FIG. 3 illustrating a pawl bouncecondition; and

FIG, 6 is a view of the mechanism of FIG. 3 showing a fail safe lockingof the improvement in locking pawl means in accordance with the presentinvention upon the occurrence of a pawl bounce condition as illustratedin FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENT Referringfirstly to FIGS. 1 and 2, the preferred exemplary embodiment ofemergency locking safety belt retractor mechanism in which theimprovement of the present invention is illustrated as indicatedgenerally at 10. The illustrative retractor mechanism includes a safetybelt or webbing ll wound upon a reel or drum (not shown) fixed about areel axle l3. Axle 13 is journled in retractor frame 14 which, as isconventional, is of a generally U-shaped configuration including base 15and parallel, spaced side walls 16 and 17. A cross brace 18 is providedfor added rigidity for the retractor frame,

The retractor mechanism of FIGS. 1 and 2 may be installed inconventional manner in a vehicle, such as an automobile, by bolting base15 at the anchor portion 19 to the vehicle frame. The retractormechanism, indicated generally at 10, is normally positioned in thevehicle adjacent a passenger seat in a position to mount the vehicleinertia means in operative condition (as more fully disclosedhereinafter) and to position the safety belt or webbing 11 for aprotraction about the vehicle passenger. As is normal in retractormechanisms of this type, the retractor reel is biased toward a beltre-wound or retracted condition by a clock type spring provided inassociation with axle 13 within a housing 20 mounted to the frame sidewall 17.

A pair of ratchet wheels or members 21 and 22, as best seen in FIG. 1,are provided in association with the reel and axle 13 to facilitatelocking the reel against protraction of the webbing in emergencysituations. As is conventional heretofore, each of the ratchet wheelmembers 21 and 22 is provided with a plurality of teeth 23 and 24respectively,

In prior art retractor mechanism constructions, it has been common toemploy a single locking pawl, and in some instances two separate lockingpawls, acting indpendently of one another, for engaging a reelassociated ratchet member, as members 21 and 22 herein, for causinglockup of the mechanism and preventing further protraction of thewebbing 11. As will be discussed hereinafter in detail, the improvementin locking pawl means of the present invention includes the provision ofa dual locking pawl assembly wherein there is cooperation between a pairof locking pawls for causing lockup in a fail safe manner in spite ofpotential pawl bounce conditions. One of such locking pawls is pro videdin the exemplary embodiment by a locking bar 25 mounted for pivotalmovement about its ends 26 and 27 mounted in co-operating slots (morefully explained hereinafter) provided in the retractor frame side walls16 and I7. Locking bar 25 is provided with a pair of spaced lockingpawls, positioned to engage the pair of ratchet wheel members 21 and 22,one of such pawls being seen at 28 in FIGS. 2 through 6.

Inertia responsive means are provided in the exemplary embodiment ofretractor mechanism for actuating locking bar 25, and its associatedlocking pawls, into engagement with the teeth 23, 24 of ratchet members21 and 22, respectively. In the exemplary embodi ment, an otherwiseconventional vehicle inertia reponsive type mechanism is illustratedgenerally at 30 and includes a pendulum 31 having a mass 32 suspended bystem or neck 33 from the head or actuator member 34. As best seen inFIGS. 3 through 6, the head or actuator member 35 seats upon a supportplate 35 with the stem or neck portion depending through an aperture 36pro vided in the support. As seen in FIG. 2, side wall 16 has adepending portion 16 which protects mass 32 from interferingrelationship with a retractor housing or other possibly interferingmeans when the retractor has been installed in a vehicle for itsintended use.

As is particularly contemplated within the present invention, a duallocking pawl assembly which is believed to be fail safe is provided inthe heretofore otherwise conventional mechanism described in order toassure prompt lockup of the retractor mechanism in the event of anemergency condition arising. Such dual locking pawl assembly includesthe provision of first and second locking pawls and means for mountingeach to the retractor mechanism in position to be moved into engagementwith the ratchet teeth of the ratchet members, the first pawl beingoperated by the inertia responsive means indicated generally at 30 andthe second locking pawl being operated by a movement of the firstlocking pawl which occurs when the first ratchet pawl bounces off of aratchet tooth in a deflective movement away from the ratchet member aswill now be explained in detail.

The first locking pawl of the dual locking pawl assembly of the presentinvention is provided by either, or both of the pawls provided upon thelocking bar 25. As seen in FIG. 3, when the retractor mechanism is in atrest condition, a depending pin or dimple 36 on the underside of lockingbar 25 rests in an upwardly facing dished support surface 37 of actuator34. In an emergency'situation, upon sudden change of vehicle inertia,the mass 32 of the inertia responsive means will be set in motioncausing actuator 34 to pivot upon support 35, raise locking bar pin 36as seen in FIG. 4 and thus pivot the associated pawls, as pawl 28, intoa locking relation to the reel associated ratchet members, as member 22in FIG. 4. In this normal operation of the within dual locking pawlassembly, the locking bar 25, and associated pawls pivot about the barends 26, 27 where they rest in the lower rear portions of the barmounting slots provided in the retractor frame side walls I6 and 17.Referring specifically to FIGS. 3 and 4, slot or cut out 38 in side wall17 (duplicated in side wall 16 but not shown) has a lower rearwardportion (to the left in FIGS. 3 and 4) about which the lower rear edgeportions of the associated bar end pivots. However, it should be notedthat slot 38 is provided with an arcuate portion 39 which allows suchrearward lower portions of the bar ends freedom of movement in averticle direction in FIGS. 3 through 6 to facilitate a pivotingmovement of the locking bar in an unconventional manner as part of thenovel operation and cooperation between the dual locking pawl or barassembly of the present invention. Such movement of the lock bar isillustrated in FIG. 6 and will be discussed in more detail hereinafter.

Second locking pawl means of the dual locking pawl assembly is providedin the exemplary embodiment by the provision of the second locking bar40 which is provided with means for mounting it to the retractormechanism in a position to be moved into engagement with the ratchetteeth by the first locking pawl means upon the occurrence of a pawlbounce condition with regard to the latter. The locking bar 40 ismounted by its respective ends 4] and 42 in co-operating slots providedin the retractor frame side walls 16 and 17 respectively. As seen inFIGS. 3 through 6, each slot, as slot or cutout 43, is provided in therespective side walls. as side wall 17 for slot 43, to pivotally mountthe locking bar for pivotal movement about a lower rear edge portion ofthe ends 41 and 42. As seen in FIG. 3, slot 43 is formed with agenerally mating configuration at 44 to restrain bar 40 to pivotalmovement about a generally fixed axis adjacent its rearward edgeportions (as seen by comparing FIGS. 3 through 5 with FIG. 6). Lockingbar 40 is provided with a pair of locking pawls 45 and 46 as seen inFIG. 1.

As also contemplated within the present invention, the dual locking pawlmeans or assembly of the present invention includes the provision of thetwo locking bars 25 and 40, and thus their associated pawls, in agenerally overlying or piggyback relationship as best seen in FIGS. 3through 6. The forward portions of locking bar 40, provided by the pawlportions 45 and 46, as pawl 45 is in FIGS. 3 through 6, overly rearwardportions of the first locking bar 25, including specifically a pair ofrearwardly extending abutment portions 47 and 48 formed in bar 25. Theseabutment portions 47 and 48 extend rearwardly of the associated pawlsprovided in the locking bar 25 and, in the preferred exemplaryembodiment, are provided with embossments 49 and 50, respectively, tofacilitate abutting engagement with the underside of the pawls 45 and 46of locking bar 40, as seen in FIG. 6. This will occur during pivotingmotion of the lock bar 25 from the condition of FIG. 5 to that of FIG. 6as will now be explained.

It has been found that during the dynamic conditions attendant emergencysituations in locking seat belt retractors to hold the associatedpassenger in his vehicle seat, that it is possible for the leading edgeor tip of the locking pawl to make contact with the leading edge or tipof the first adjacent tooth of the ratchet teeth and, rather thanlocking the retractor via engagement with that particular tooth, a pawlbounce or unlocking motion is imparted to the locking pawl due to themomentum of the ratchet wheel which causes the pawl to move in adeflective unlocking motion away from the ratchet wheel. This pawlbounce or locking failure condition is illustrated in FIG. 5. While itis likely that the pawl would then lock in the next successive ratchettooth, it is preferred that the attendant protraction of seat beltwebbing due thereto be avoided if possible. In accordance with thepresent invention, when the pawl bounce condition of FIG. 5 occurs, thelocking bar 25 and associated pawls will be pivoted by the impact of theleading tip of tooth 24' to cause the locking bar to pivot about pin 36and thereby raise abutment portion 47, and its associated embossment 49beneath the associated pawl of lock bar 40 to pivot the latter into thecondition of FIG. 6 and locking engagement with the tooth 24'. Suchpivoting movement for lock bar 25 is facilitated through the provisionof the dished surface 37 on actuator 34 beneath bar pin 36 and.importantly, the provision of the arcuate portion 39 of slot 38. Thedual locking bar and pawl assembly thus provided by locking bars 25 and40, and their associated pawls, assures a positive lock up of theretractor reel promptly under emergency conditions through the novel cooperation between the two locking bars and associated pawls.

I claim:

1. A fail safe locking mechanism for emergency locking safety beltretractors having a primary locking pawl for preventing belt protractionfrom the retractor by engaging a tooth of a ratchet wheel member havinga plurality of ratchet teeth and comprising:

a fail safe pawl and means for mounting it to said retractor in positionto be moved to engage with teeth of said ratchet wheel member; and

means for moveably mounting said primary locking pawl to provide for itsmovement against said fail safe pawl to move the latter into engagementwith a ratchet tooth of said ratchet member upon a deflective movementof said primary locking pawl relative to said ratchet member, as whensaid locking pawl engages a tip of a ratchet tooth and is deflected awayfrom said ratchet member.

2. The fail safe locking mechanism of claim 1 wherein:

said fail safe pawl mounting means mounts said fail safe pawl with aforward portion thereof in overlying relation to a rearward portion ofsaid locking pawl.

3. The fail safe locking mechanism of claim 2 wherein:

said means for moveably mounting said locking pawl includes means forpivotally mounting said locking pawl for pivotal movement about anapproximate midportion thereof between forward and rearward portions ofsaid locking pawl to provide a pivotal movement to said locking pawlrearward portion upon said deflective movement.

4. The fail safe locking mechanisms of claim 1 wherein a vehicle inertiaresponsive means is provided with an actuator member for moving saidlocking pawl into engagement with said ratchet wheel member upon changeof vehicle inertia and wherein said means for mounting said locking pawlincludes the provision of pivot means between said locking pawl and saidactuator member and mounting slots in the retractor for retaining saidlocking pawl therein and allowing for pivotal motion of both forward andrearward portions thereof.

5. The fail safe locking mechanism of claim 1 wherein:

said locking pawl is provided with embossment means on the rearwardportion thereof for engagement with the underside of said fail safe pawlgenerally adjacent a forward portion thereof.

6. In an emergency locking safety belt retractor mechanism including abelt winding reel, at least one reel associated ratchet member having aplurality of ratchet teeth, locking pawl means mounted for engaging theratchet teeth of said ratchet member on actua tor thereof and emergencyresponsive means for actuating said pawl to lock said reel via saidratchet memher. the improvement in locking pawl means comprising theprovision of:

a dual locking pawl assembly including first and second locking pawlsand means for mounting each to said mechanism in position to be movedinto engagement with said ratchet teeth. said first pawl 8 beingoperated by said emergency responsive means; and

means for actuating said second locking pawl by the defective movementof said first locking pawl in the event said first locking pawl strikesa ratchet tooth tip and is defected thereby upon actuation from saidemergency responsive means.

7. The improvement in locking pawl means of claim 6 wherein said meansfor actuating said second locking pawl by said first locking pawlincludes the provision of abutment means on a rearward portion of saidfirst pawl underlying a forward portion of said second locking pawl andsaid first locking pawl is pivotally mounted to pivot said abutmentmeans against said second pawl forward portion.

1. A fail safe locking mechanism for emergency locking safety belt retractors having a primary locking pawl for preventing belt protraction from the retractor by engaging a tooth of a ratchet wheel member having a plurality of ratchet teeth and comprising: a fail safe pawl and means for mounting it to said retractor in position to be moved to engage with teeth of said ratchet wheel member; and means for moveably mounting said primary locking pawl to provide for its movement against Said fail safe pawl to move the latter into engagement with a ratchet tooth of said ratchet member upon a deflective movement of said primary locking pawl relative to said ratchet member, as when said locking pawl engages a tip of a ratchet tooth and is deflected away from said ratchet member.
 2. The fail safe locking mechanism of claim 1 wherein: said fail safe pawl mounting means mounts said fail safe pawl with a forward portion thereof in overlying relation to a rearward portion of said locking pawl.
 3. The fail safe locking mechanism of claim 2 wherein: said means for moveably mounting said locking pawl includes means for pivotally mounting said locking pawl for pivotal movement about an approximate midportion thereof between forward and rearward portions of said locking pawl to provide a pivotal movement to said locking pawl rearward portion upon said deflective movement.
 4. The fail safe locking mechanisms of claim 1 wherein a vehicle inertia responsive means is provided with an actuator member for moving said locking pawl into engagement with said ratchet wheel member upon change of vehicle inertia and wherein said means for mounting said locking pawl includes the provision of pivot means between said locking pawl and said actuator member and mounting slots in the retractor for retaining said locking pawl therein and allowing for pivotal motion of both forward and rearward portions thereof.
 5. The fail safe locking mechanism of claim 1 wherein: said locking pawl is provided with embossment means on the rearward portion thereof for engagement with the underside of said fail safe pawl generally adjacent a forward portion thereof.
 6. In an emergency locking safety belt retractor mechanism including a belt winding reel, at least one reel associated ratchet member having a plurality of ratchet teeth, locking pawl means mounted for engaging the ratchet teeth of said ratchet member on actuator thereof and emergency responsive means for actuating said pawl to lock said reel via said ratchet member, the improvement in locking pawl means comprising the provision of: a dual locking pawl assembly including first and second locking pawls and means for mounting each to said mechanism in position to be moved into engagement with said ratchet teeth, said first pawl being operated by said emergency responsive means; and means for actuating said second locking pawl by the defective movement of said first locking pawl in the event said first locking pawl strikes a ratchet tooth tip and is defected thereby upon actuation from said emergency responsive means.
 7. The improvement in locking pawl means of claim 6 wherein said means for actuating said second locking pawl by said first locking pawl includes the provision of abutment means on a rearward portion of said first pawl underlying a forward portion of said second locking pawl and said first locking pawl is pivotally mounted to pivot said abutment means against said second pawl forward portion. 